Method for producing fluoropolymer, method for producing polytetrafluoroethylene, method for producing perfluoroelastomer, and composition

Abstract

The present disclosure provides a method for producing a fluoropolymer, the method includes polymerizing a fluoromonomer in an aqueous medium in the presence of a polymer (1) to obtain a fluoropolymer, wherein the polymer (1) is a polymer of a monomer (1) represented by the general formula (1) below, in which the content of a dimer and a trimer of the monomer (1) is 1.0% by mass or less based on the polymer (1): CF2═CF—R—CZ1Z1-A0  (1) wherein R is a linking group; Z1 and Z2 are each independently F or CF3; and A0 is an anionic group.

What is claimed is: 
     
         1 . A method for producing a fluoropolymer, the method comprising polymerizing a fluoromonomer in an aqueous medium in the presence of a polymer (1) to obtain a fluoropolymer, wherein
 the polymer (1) is a polymer of a monomer (1) represented by the general formula (1) below and has a number average molecular weight of 0.3×10 4  or more, in which a content of a dimer and a trimer of the monomer (1) is 1.0% by mass or less based on the polymer (1):
   CF 2 ═CF—R—CZ 1 Z 2 -A 0   (1)
 
   wherein R is a linking group; Z 1  and Z 2  are each independently F or CF 3 ; and A 0  is an anionic group,   polymerizing the monomer (1) represented by the general formula (1) to obtain a crude composition containing the polymer of the monomer (1); and   removing the dimer and trimer of the monomer (1) contained in the crude composition from the crude composition to obtain the polymer (1) in which the content of the dimer and trimer of the monomer (1) is 1.0% by mass or less based on the polymer (1).   
     
     
         2 . The method for production according to  claim 1 , wherein the monomer (1) is a monomer (2) represented by the following general formula (2):
   CF 2 ═CF—R—CZ 1 Z 2 —COOM  (2)
   wherein R is a linking group; Z 1  and Z 2  are each independently F or CF 3 ; M is H, a metal atom, NR 7   4 , imidazolium optionally having a substituent, pyridinium optionally having a substituent, or phosphonium optionally having a substituent; and R 7  is H or an organic group.   
     
     
         3 . The method for production according to  claim 1 , wherein the monomer (1) is a monomer (4) represented by the following general formula (4):
   CF 2 ═CF(—O—Rf-A)  (4)
   wherein Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and having an ether bond or a keto group; and A is —COOM, —SO 3 M, —OSO 3 M, or —C(CF 3 ) 2 OM, where M is H, a metal atom, NR 7   4 , imidazolium optionally having a substituent, pyridinium optionally having a substituent, or phosphonium optionally having a substituent, and R 7  is H or an organic group.   
     
     
         4 . The method for production according to  claim 3 , wherein A is —COOM, where M is H, a metal atom, NR 7   4 , imidazolium optionally having a substituent, pyridinium optionally having a substituent, or phosphonium optionally having a substituent, and R 7  is H or an organic group.